Capture One Pro 21 is now available for pre-order for existing customers. Several different upgrade/purchase options are available depending on the version owned (you will need to login to your account in order to upgrade):
Capture One did not provide any information on the new features in version 21. Stay tuned for that. The 20% off coupon will be available only on pre-orders, once version 21 is released, the coupon will no longer be valid.
Via NikonRumors